Hi Matt,

Yes, your pdf looks right, though I didn't check in very fine detail.
I'll send my post and the file to support.
Don't bother to read through the code. Most of what I see is sensible, though I'm not too sure about how the anacrusis is supposed to be coded. I'd need to look further into that. I'd imagine that the bar length is shorter for it and some tools don't handle that as they should.

MuseScore 4(.0.0) seems to be much less good at making good scores from MXL that MuseScore 3 did. I suspect the parse->render stage rather than the parsing as the latter is probably common. 4.0.2 may be better, I have yet to check.

I always have slight concerns with MusicXML because the standard combines so many of the issues that MIDI can have with a whole new bunch of things for chords and rendering. There are lots of places to get things wrong. IIRC the last time I played around with it (I can't now remember why) I used a Python library.

Jazz relative beginner, starting at a much older age than was helpful.
AVL:MXE Linux; Windows 11
BIAB2025 Audiophile, a bunch of other software.
Kawai MP6, Ui24R, Focusrite Saffire Pro40 and Scarletts
.